Pseudomonas aeruginosa is an opportunistic bacterial pathogen that is capable of causing fatal acute lung infections in critically ill individuals (1). The ability of the bacterium to damage the lung epithelium has been linked with the expression of toxins that are directly injected into eukaryotic cells via a type III-mediated secretion and translocation mechanism (2, 3).
The proteins encoded by the P. aeruginosa type III secretion and translocation apparatus demonstrate a high level of amino acid identity with members of the Yersinia Yop regulon (4-6). Of all the type III systems discovered in Gram-negative bacteria, only P. aeruginosa possesses a homologue to the Yersinia V antigen, PcrV (see 6 for review of type III systems). Homologous proteins to the secretion and translocation apparatus are encoded by both plant and animal pathogenic bacteria. These organisms include human pathogens such as Salmonella typhimurium, Shigella flexneri, Enteropathogenic E. coli, Chlamydia spp., and plant pathogens such as Xanthamonas campestris, Pseudomonas syringae, Erwinia amylovora and Ralstonia solanacearum. However, only P. aeruginosa and Yersinia encode the V antigen.
Yahr, et al., 1997, discloses the sequence of the operon encoding PcrV and compares the sequence to the LcrV protein. Thus, the amino acid sequence of PcrV is known and is available under accession number AF010149 of GenBank.
The present invention involves methods and compositions developed from our observation that the Pseudomonas V antigen can be used to protect animals from a lethal lung infection.
In one embodiment, the present invention is a method of inhibiting Pseudomonas infection comprising inoculating a patient with an effective amount of PcrV antigen. In another embodiment, DNA encoding PcrV is used as a gene vaccine.
In one preferred embodiment, the antigen is expressed as a recombinant protein and used to immunize patients at risk.
Preferably, the patient is completely protected from infection.
In another embodiment, the DNA encoding PcrV (called pcrV) or a DNA fragment may be used diagnostically to detect P. aeruginosa infection.
In another embodiment, the recombinant protein (rPcrV) is used diagnostically to detect antibodies from patients. Patient antibody response to PcrV may be associated with prognosis. Therefore, in this embodiment the recombinant protein is used as a prognostic indicator by measuring the patient""s antibody titer.
The present invention also provides a method for inhibiting a Pseudomonas infection in an individual by contacting the individual with an effective amount of a PcrV inhibitor, in particular with a PcrV antibody, antibody derivative or fragment, or antibody mimic. PcrV antibodies, antibody derivatives and antibody fragments are also provided.
It is an object of the present invention to actively and passively immunize a patient against Pseudomonas infection.
It is another object of the present invention to diagnostically detect the P. aeruginosa infection.
It is another object of the present invention to diagnostically detect antibodies from Pseudomonas patients.
Other objects, features and advantages of the present invention will become apparent to one of skill in the art after review of the specification, claims and drawings.